Automatic plywood layup machine

ABSTRACT

An automatic plywood layup line is disclosed which is comprised of a plurality of vertically spaced generally horizontal in-line conveyor surfaces, each having an input end and output end. Several conveyor surface loader systems are laterally spaced from the conveyor surfaces and are adapted to spread selected veneer sheets with glue and place them over the input ends of the respective conveyor surfaces. At the output ends of the conveyor surfaces are a pair of sheet positioners which serve to position each individual sheet over a layup stations as it is motivated outwardly from the end of the central conveyor system. AT the layup stations two men may be provided for guiding the veneer sheets onto the stack of forming panels and also to visually scan each individual sheet in order to minimize rejects.

April 3, 1973 B BROOKHYSER ET AL 3,725,183

AUTOMATIC PLYWOOD LAYUP MACHINE Filed March 29, 1971 3 Sheets-Sheet 1 BYWk,

TTORNE V April 1973 B. BROOKHYSER ET AL 3,725,183

AUTOMATIC PLYWOOD LAYUP MACHINE Filed March 29, 1971 3 Sheets-Sheet 2BYRON B. BROOK/1K5? #49010 5 ER/CKSO/Y GLEN R PERRY TOR/V E V April 3,1973 B. BROOKHYSER ETAL I 3,725,183

AUTOMATIC PLYWOOD LAYUP MACHINE Filed larch 29, 1971 3 Sheets-Sheet 5//VVEN7'0F$, BYRON B. BFOOKHVSEI? HAROLD E EE/CKSON GLEN K PERI? wake?ATTORNEY United States Patent AUTOMATIC PLYWOOD LAYUP MACHINE Byron B.Brookhyser, Milton, Harold E. Erickson, Federal Way, and Glenn R. Perry,Tacoma, Wash., as-

signors to Weyerhaeuser Company, Tacoma, Wash.

Filed Mar. 29, 1971, Ser. No. 128,780

Int. Cl. B32b 31/04; B65g 57/00 US. Cl. 156--563 3 (ilaims ABSTRACT OFTHE DISCLOSURE An automatic plywood layup line is disclosed which iscomprised of a plurality of vertically spaced generally horizontalin-line conveyor surfaces, each having an input end and output end.Several conveyor surface loader systems are laterally spaced from theconveyor surfaces and are adapted to spread selected veneer sheets withglue and place them over the input ends of the respective conveyorsurfaces. At the output ends of the conveyor surfaces are a pair ofsheet positioners which serve to position each individual sheet over alayup station as it is motivated outwardly from the end of the centralconveyor system. At the layup station two men may be provided forguiding the veneer sheets onto the stack of forming panels and also tovisually scan each individual sheet in order to minimize rejects.

BACKGROUND OF THE INVENTION This invention relates generally to amachine which seq-uentially conveys and then stacks individual thinsheets such as wood veneer. More particularly, the invention relates toan automatic plywood layup line that conveys individual veneer sheetsselectively spread with glue to a layup station where plywood panels areformed.

Plywood is, as those skilled in the art know, comprised of a pluralityof wood veneer sheets glued together with adjacent veneer sheets havingtheir respective grains running in transverse directions. Generally, aplywood panel is formed by sequentially stacking the individual veneersheets one atop the other with the appropriate glue lines in place. Forexample, in a three-ply panel an individual back veneer is positioned ona surface and then an individual core or cross band sheet is placed atopthe back and finally the face sheet is placed atop the core. It will beappreciated that a coating of glue can be applied. to either of thesurfaces which come in contact with one another. For example, both sidesof the core veneer could be coated with glue. After the three sheets ofveneer are sequentially arranged, the panel is pressed and the glue isallowed to cure.

In the formation of plywood having more than three plies, for example, afive-ply panel and all odd ply panels, an additional sheet or sheets ofveneer is utilized. In forming a five-ply panel a back would first belaid, then a core veneer sheet, then a center sheet, then another coresheet and finally the face sheet atop the second sheet of core veneer.Again, appropriate glue lines are established between adjacent veneersheets. The general formation of plywood panels is well understood bythose skilled in the art and a further description of plywool formationis not deemed necessary to an understanding of the present invention.

The prior art offers many automatic layup machines capable of formingplywood panels without the old utilization of the normal manual labor.Several examples of prior art automatic layup machines may be seen byreferring to the US. patent issued to C. C. Clapp et al.- 3,312,327 andUS. Patent 3,247,042 issued to E. B. Denton et al. Both of these citedpatents are assigned to the same assignee as is the present invention.

Of course, it can readily be appreciated that one purpose of mechanizingplywood layup is to reduce manual labor and thereby reduce such laborcosts. An additional reason for mechanizing plywood layup is to increasethe production of plywood panels.

In view of the fact that the veneer sheets are very thin, extremelyflexible and have rough surfaces, as the speed of a plywood layupmachine increased, the number of reject panels resulting also tended toincrease. A machine was needed that provided the usual desired purposesfor a layup machine but which also reduced the rejects resulting fromrapid plywood formation.

Another attendant problem with prior art layup machines was that theytended to take up a large amount of floor space within the plywoodplant. In addition to the above-mentioned purpose of reducing rejects, alayup machine was needed that could be installed within a small amountof floor space.

Accordingly, from the foregoing, one object of the present invention isto provide an improved plywood layup machine that results in fewerrejects.

Another object of the invention is to provide a plywood layup machinewhich utilizes a small amount of plant floor space.

An additional object of the invention is to provide the above twomentioned objects, while maintaining a high rate of production. Otherobjects and advantages will become apparent from the followingdescription of a preferred embodiment of the invention which isillustrated in the accompanying drawings.

SUMMARY OF THE INVENTION Briefly stated, the present invention ispracticed in one form by providing a plurality of horizontal conveyorsurfaces positioned generally in line and spaced apart, one atop theother. In addition, conveyor loaders are provided at the input ends ofeach conveyor surface and they sequentially position a sheet of veneeron the input end of the respective conveyor surface. Glue lineapplicators are positioned between the conveyor loaders and theirrespec- .tive conveyor surfaces and as an individual sheet of veneer ismotivated from the conveyor loader to the conveyor surface, it receivesa glue line on one surface. Finally, a layup station is provided at theoutput ends of the conveyor surfaces to receive the individual veneersheets as they are conveyed off of their respective conveyor surface andonto a forming stack. At the layup station, two men are positionedopposite one another and on either side of the output ends of theconveyor surfaces in order to scan each individual veneer sheet as itfalls onto the forming stack.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a simplified schematicrepresentation of the several conveyor surfaces together with theattending conveyor loaders, glue applicators and layup station.

FIG. 2 is a side elevation view of the central conveyor system showingthe face loader and also the layup station.

FIG. 3 is a plan view looking straight down showing the several conveyorloader areas together with the floor plan of the central in-lineconveyor system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1 thepresent invention will be described in general terms according to thelayout of the elements of the plywood layup machine. Before proceedingit should be appreciated that the ultimate object of any plywood layupmachine is to produce plywood panels having a predetermined number ofplies which are of suflicient quality and integrity to meet minimumindustry standards. During the accomplishment of this object, the onlyphysical change occurring to the veneer sheets is that selected sidesare coated with a layer of glue so that when the veneer sheets are laidup to form the panels the proper adhesive quantity and quality will bepresent to join the veneer sheets together.

The central conveyor system is generally indicated as 1 and is comprisedof a plurality of horizontally extending in-line conveyor surfacespositioned one atop the other and indicated respectively, from top tobottom, as 2, 3 and 4. Each of the conveyor surfaces 2, 3 and 4 will beindividually described in general terms in relation to the overallconveyor system 1. Additional details of the con veyor surfaces will bedescribed when referring particularly to FIGS. 2 and 3.

The top conveyor surface 2 is comprised of a plurality of individualendless flat belts, each indicated as 5. Of course, it will beappreciated that the flat belts 5 are maintained in a fixed travelposition by any suitable frame and train means. The endless flat belts 5are likewise driven by any suitable drive means (not shown) such as amotor driven shaft about which the flat belts are trained. The primaryrequirement for the drive means is that it motivate the conveyor surface2 and its flat belts 5 in a direction from left to right as indicated bythe directional arrows in FIG. 1. Prior to taking up a description ofthe middle conveyor surface 3, it is to be noted that the entire topconveyor surface 2 moves up and down in order to engage a veneer sheetfor proper conveyance. This feature will be more fully described later.In the embodiment shown, the top conveyor surface 2 is pivotally mountedat one of its ends.

Each conveyor surface has an input end and an output end with the inputend of the top conveyor surface 2 being generally indicated at 6. Theoutput end of the top conveyor surface is generally indicated at 7. Ofcourse, it will be appreciated that the top conveyor surface 2 will becharged with a veneer sheet at its input end 6 and then conveyed to itsoutput end 7 where it then is directed to a layup station 8.

Turning now to a description of the middle conveyor surface 3, it ispositioned in line and vertically below the top conveyor surface 2.Conveyor surface 3 is also comprised of a plurality of endless flatbelts indicated as 9 and the conveyor surface 3 may likewise be drivenby any suitable means desired. The middle conveyor surface 3 isgenerally longer in a horizontal direction as will be apparent whendescribing the middle conveyor surface loader. Although not specificallyapparent from FIG. -1 a portion of the middle conveyor surface 3 ispivotally mounted so as to pivot up and down in order to sequentiallycommunicate with the top conveyor surface 2. The pivoting portion of themiddle conveyor surface 3 is generally indicated as 10. The middleconveyor surface 3 receives veneer sheets at an input end 11 and thenconveys them linearly to an output end indicated as 12 which forms apart of the pivotal portion of the middle conveyor surface 3. It will,therefore, be appreciated that the pivotal portion 10 also forms a partof the top conveyor surface 2 when it is in its raised position. When itis in the bottom position, it is generally horizontal and forms aportion of the middle conveyor surface 3. Thus, the output ends of boththe top and middle conveyor surfaces are comprised of the same portionof pivotal con veyor surface 10. It should be appreciated by one skilledin the art that the pivotal feature of the output end of the top andmiddle conveyor surfaces is not an absolute necessity to the function ofthe present invention. It would, for example, be possible to extend thetop conveyor surface horizontally such that there would be threeconveyor surfaces ending generally at the same horizontal position. Byusing the pivotal portion 10 of the middle 4 conveyor surface 3 as inthe present embodiment, it is possible to save building material andalso to eliminate additional elements at the layup station 8.

The bottom conveyor surface 4 unlike the top and middle conveyorsurfaces, is comprised of a plurality of axially spaced powered rollerseach indicated as 13. The bottom conveyor surface 4 comprised of thepowered rollers 13 also has an input end generally indicated as 14 and acorresponding output end 15 which is at the same horizontal position asare the output ends of the top and middle conveyor surfaces. It will beappreciated that the powered rollers 13 may be driven by any suitablemeans such as a motor driving a continuous chain linking each poweredroller 13. The powered rollers 13 are mounted in a suitable frame whichmay be seen when referring to FIGS. 2 and 3 and the supporting frameprovides the fiat horizontal nature of conveyor surface 4.

Before generally describing the device utilized to position eachindividual veneer sheet at the layup station 8, it should be mentionedthat the composition of the several conveyor surfaces can be comprisedof different elements. For example, top conveyor surface 2, instead ofbeing comprised of a plurality of endless flat belts 5, could becomprised of a plurality of powered rollers just as conveyor surface 4.Likewise, conveyor surface 4 comprised of powered rollers 13 could becomprised of a plurality of flat belts. Any device that Will convey aveneer sheet from an input end in a linear manner to its output end withsufficient momentum is within the scope of the generically termedconveyor surfaces.

Next to be described are the veneer positioners which are generallyindicated at 16 and are adapted to cause a veneer sheet to be propelledaway from the central conveyor system 1 and properly aligned forstacking at the layup station 8. A top sheet positioner 17 is positionedbetween the end of the pivotal portion 10 of the middle conveyor and thelayup station 8. The input edge 18 of the sheet positioner 17 isgenerally in the same horizontal plane or slightly lower than the outputend of the pivotal portion 10. From the input edge '18 of the top sheetpositioner 17, a curvilinear surface is provided extending a suitabledistance axially to an output edge 19. From this description, it isreadily apparent that as individual veneer sheets are motivated alongthe top and middle conveyor surfaces 2, 3 and then to the common pivotalportion 10, the individual sheets will be propelled across thecurvilinear surface of the top sheet positioner 17. As previouslymentioned, the drive means for the conveyor surfaces are selected suchthat a sufficient amount of momentum is imparted to the individualsheets as they are propelled across the surface of the top sheetpositioner 17. The ideal momentum is just enough to cause the trailingedge of an individual veneer sheet to leave the output edge 19 of thetop sheet positioner 17. The details of the top sheet positioner 17 arefully described in a copending application having Ser. No. 128,779entitled Sheet Positioner and on which a Notice of Allowance has beenreceived from the 'Patent Oflice.

A bottom sheet positioner 20 is similarly arranged to accept veneersheets from the output end 15 of the bottom conveyor surface 4. Thedetails of the bottom sheet positioner 20 are not shown in FIG. 1, butrather are indicated in FIG. 2 and are in fact the subject of an issuedUS. Pat. 3,674,256 entitled Thin Sheet Thrower and assigned to thepresent assignee. The function of the bottom sheet positioner 20 is toaccept the conveyed veneer sheets from the bottom conveyor surface 4 andthen direct them to the proper position over the layup station 8.Although the details of the sheet positioner 20 as shown in FIG. 2depict a sheet thrower assembly, it will be appreciated that the bottomsheet positioner may be comprised of a curvilinear surface similar tothe top sheet positioner 17 without departing from the scope of thepresent invention.

It is apparent then that the intent of the sheet positioner area 16 isto direct in a sequential manner individual veneer sheets to a positionover the layup station 8. At the layup station 8, two men are positionedon either side thereof in order to catch the individual veneer sheets asthey travel from the sheet positioners 17, 20 to the stack of veneersheets 21 which is being continually built up thereby forming thesequentially arranged plywood panels. Their function is to guide thesheets from the position over the stack 21 provided by the respectiveconveyor surface and sheet positioner to the top of stack 21. Theposition provided by the conveyor surfaces and sheet positioners isgenerally in a horizontal plane disposed vertically above the top of theveneer stack 21. At this position, the two men will clutch the veneersheet on either side therof and guide it downwardly as it falls underthe influence of gravity to the top of veneer stack 21. A fixed verticalsurface or backstop 22 is provided as an additional positioning meansfor the stack being formed and the trailing edge of each veneer sheet isguided downwardly so that it abuts the backstop22 thereby forming onestraight side to the stack 21. An airstop member 22a extends verticallyupward adjacent the downstream side of stack 21 and is axially spacedtherefrom a slight distance.

It is also the function of the two men to visually scan each veneersheet as it comes from the sheet positioners 17, 20 for any defectswhich are serious enough to eliminate it from the stack 21. Byeliminating individual veneer sheets which are not suitable for plywoodpanels, it will be readily apparent that rejects are virtuallyeliminated prior to pressing and curing.

An additional characteristic of the veneer stack 21 is that it is beingbuilt up on a vertically adjustable flat bed 23. The vertical positionof the flat bed 23 is adjusted as the veneer stack 21 increases inheight, that is, as the stack continues to build up, the flat bed 23will be lowered accordingly such that the two men will still be in 'aposition to handle each veneer sheet and guide it to the top of stack21.

The veneer stack 21 is built up of individual veneer sheets until asuitable number of pre-pressed panels are formed for final pressing andcuring into plywood panels. After the press cycle, the normal procedureis to trim the plywood panels to their finished size which in the normalcase is 4 feet by 8 feet. i

' Turning nowto a general description of the conveyor surface loadermeans and their associated glue spreaders, it may be seen'by referringto FIG. 3 that the conveyor surface loaders are laterally spaced fromtheir respective conveyor surfaces. The purpose of each surface loaderis to provide an individual veneer sheet at the input end of therespective conveyor surface. j

The face conveyor surface loader, which is generally indicated at 24,may be of any suitable type known to the art. For example, one suitablemechanism for loading face veneer sheets may be seen by referring to theissued US. patent to C. C. Clapp et ale- 3,312,327 and which is assignedto the assignee of the present invention. The disclosure relating tothevacuum pickup and transfer assembly is incorporated by reference herein.Although the mechanical face conveyor loader is not shown in FIG. 1,

it is generally indicated in FIGS. 2 and 3. The details of themechanical mechanism are not shown since they are not material to anunderstanding of the present invention,

but they may be seen by referring to the aforementioned worked it isdesirable to have a: second stack of face veneer sheets 26 ready to takeup the position of the working stack when itbecomes exhausted. Ideally,as the last face sheet is loaded from the working stack of veneer sheets25 the second stack 26 will automatically be conveyed into the workingposition directly adjacent the input end 11 of the middle conveyorsurface. In this manner when the face conveyor surface loader 24 isready to load another face sheet it will have a ready supply without anynecessity for halting the operation of the total conveyor system 1. Anadditional characteristic of the stack of face veneer sheets 25 is itsability to adjust itself to the level of the middle conveyor surface 3as the face loader 24 picks individual sheets off the top. By soadjusting the vertical position of stack 25 it is apparent that the topface sheet will always be in a proper horizontal position for loadingonto the middle conveyor surface 3. Of course, the proper overallvertical position of the stacks of face veneer sheets 25, 26 can easilybe provided by a raised platform indicated as 27.

Turning now to a general description of the center-back conveyor surfaceloader which is indicated at 28, it will be appreciated that its primaryfunction is to position an individual back or center veneer sheet on thetop conveyor surface 2 at its input end 6. The center-back loader 28 isgenerally on the same horizontal plane as is the top conveyor surface 2and is arranged and adapted to charge the input end 6 of the topconveyor surface 2 with an individual veneer sheet with its longerdimension perpendicular to its direction of travel as it is conveyeddown the top conveyor surface 2 toward the top sheet positioner 17.

A portion of the center-back loader 28 is comprised of a center-backentrance conveyor surface indicated as 29. The entrance conveyor surface29 extends outwardly from and at right angles to the top conveyorsurface 2 and is positioned in a horizontal plane slightly above the topconveyor surface 2 when it is in its lower position prior to conveyingthe center or back veneer sheet. The entrance conveyor surface 29 iscomprised of a plurality of powered rollers 30 which may be driven byany suitable means such as a motor and interconnected drive chain (notshown). It is to be noted that as the entrance conveyor surface 29 andits associated powered rollers 30 motivate an individual back or centersheet toward the input end of the top conveyor surface 2 it willgenerally position each sheet squarely over the several endless flatbelts 5 comprising the input end 6 of the top conveyor surface. Wheneach veneer sheet is positioned in such a manner the powered rollers 30are stopped and the veneer sheet will be resting in a horizontal planeslightly above the top conveyor surface 2. When the proper sequentialmoment arrives the top conveyor surface 2 will move upward slightly in apivotal manner about an axially spaced position from the input end 6.The pivotal motion is just enough to allow the veneer sheet to be liftedoff the powered rollers 30 and become engaged with the plurality ofendless flat belts 5. In this position the individual veneer sheet is,of course, ready to be conveyed down the top conveyor surface 2 towardthe top sheet positioner 17 and then onto the stack of veneer sheets 21at the layup station 8.

Also provided as part of the center-back conveyor surface loader system28 is an entrance conveyor surface charger means which is not shown inFIG. 1 but which is indicated by the reference numeral 31 in FIG. 3. Any

suitable means is within the contemplation of the present invention thatwill, in the proper sequence, position a center or back veneer sheet onthe entrance conveyor surface 29. Not only are mechanical means withinthe scope of the present invention but an individual person couldreadily position the veneer sheet over the entrance conveyor surface 29in a suitable aligned manner. Suitable mechanical means may be adaptedfrom the teaching of the aforementioned Clapp et al. patent.

From FIG. 1 it will be seen that the center-back conveyor surface loadersystem 28 is responsible for positioning both centers and backs over thetop conveyor surface 2 through using the same entrance conveyor surface29. In order to accomplish this function an individual stack of centerveneer sheets 32 is positioned along side the entrance conveyor surface29. The top sheet of stack 32 is generally on the same horizontal planeas are the plurality of powered rollers 30. On the opposite side of theentrance conveyor surface 29 is a stack 33 of individual back veneersheets. Here again the top back sheet is generally in the samehorizontal plane as is the entrance conveyor surface 29. Each of stacks32 and 33 are positioned atop a conventional scissors lift which isvertically adjustable so as to maintain the top veneer sheet in eachstack at a constant height equal to the horizontal plane of .the poweredrollers 30. The general elevation in relation to the total conveyorsystem 1 for stacks 32 and 33 is provided by a suitable raised platform34. Each raised platform 34 is large enough in order to accommodate anew stack of centers or backs so that when the working stack isexhausted the new stack can be automatically positioned adjacent theentrance conveyor surface 29 for continued operation of the totalconveyor system 1.

As has been mentioned, certain selected veneer sheets are given acoating of glue on one side thereof prior to their entry into thecentral conveyor system 1. A conventional softroll glue spreader 35 islaterally positioned along the entrance conveyor surface 29 adjacent theinput end 6 of top conveyor surface 2. As the powered rollers convey acenter or back veneer sheet toward the input end 6, it will pass throughthe softroll glue spreader and receive a coating of glue on its upperside. The glue spreader 35 is comprised of a pair of doctor rollsindicated as 36, one of which abuts'the cylindrical softroll 37, and acylindrical back-up roll 38 which is positioned vertically beneath thesoftroll. The appropriate rolls in the glue spreader 35 are, of course,powered in order to move the individual veneer sheet through the gluespreader and onto the remainder of the entrance conveyor surface 29'. Aconventional glue spreader of the type which may be used in the presentinvention can be seen by referring to the issued U.S. patent to CharlesBlickenderfer, Jr.-3,392,6-99 which has been assigned to the assignee ofthe present invention. The Blickenderfer et a1. patent is incorporatedby reference herein. An example of a suitable softroll for coating aveneer surface may be seen by referring to the U.S. Pat. 3,587,153 inthe name of Charles Blickenderfer, Jr. et a1. and which has also beenassigned to the assignee of the present invention. This issued patent isalso incorporated by reference herein.

To follow now is a general description of the core or cross bandconveyor surface loader system which is generally indicated as 39. Thecore entrance conveyor system 39 is provided in order to convey anindividual sheet of core veneer from a stack to a proper position overthe input end 14 of the bottom conveyor surface 4. By so conveying anpositioning a sheet of core veneer,

the bottom conveyor surface '4 and its associated power rollers 13 willthen be ready to move upwardly in a pivotal manner and convey the coreveneer sheet toward the bottom conveyor surface output end 15 and thebottom sheet positioner 20. The function and operation of the entranceconveyor system 39 is identical to that of the center-back conveyorsurface loader system 28. One difference in composition is that the coreentrance conveyor surface 40 is comprised of a plurality of endless fiatbelts 41 as opposed to a plurality of powered rollers. This differenceis provided to accommodate the different grain direction. With thisdesign the core veneer sheets are positioned on the input end of theentrance conveyor su'fface 40 from which they are conveyed through-asimilar softroll glue spreader 35a from which point the endless flatbelts 41 continue to convey the core veneer sheet V until it is properlypositioned and aligned over the input end 14 of the bottom conveyorsurface 4. At this point when the proper sequential moment is reachedthe bot tom conveyor surface 4 pivots upwardly to pick the core veneersheet off of the endless flat belts 41 from which position it can thenbe conveyed toward the layup station 8.

Although it is not absolutely necessary for the proper operation of thepresent invention, the core conveyor surface loader system 39 is shownutilizing two separate stacks 42 of core veneer sheets positioned oneither side of the input end of the entrance conveyor surface 40. Again,any suitable means for transferring an individual core sheet from thestacks 42 to the endless fiat belts 41 is within the contemplation ofthe present invention. If the double core stack arrangement is used orif a single core stack is utilized, it is desirable to position asecondary or replenishing stack 43 adjacent to the working stack forready replacement when the working stack 42 becomes exhausted. Again theelevation of the top core sheet on the core stack 42 is maintained atthe same vertical level as is the core entrance conveyor surface 40. Aconventional adjustable scissors lift is provided under the stack 42 toaccomplish this purpose. A properly elevated platform 44 is provided inorder to properly position the scissors lift for the adjustable heightin relation to the total conveyor system 1. The platform 44 is providedwith enough plan area to allow the secondary core stack 43 to restadjacent the working core stack 42. Appropriate openings are provided ineach of the platforms 27, 34, 44 so that a fork-lift truck can depositthe secondary or replenishing stack of veneer sheet material adjacenteach working stack.

Referring now particularly to FIGS. 2 and 3 and for reference to FIG. 1,the remaining details of the present invention will be described. Firstto be described in detail, will be the central conveyor system framewhich generally supports and provides the proper spacing for theplurality of in-line conveyor surfaces2, 3, and 4. Basic support for theconveyor system 1 is provided by an outer frame generally indicated as45 and which is comprised of spaced joined-together beams. Verticallydisplaced horizontally extending side beams 46 provide the properpositioning of the conveyor surfaces, as well as the verticalsupport..A-plurality of vertically extending beams 47,

of course, support the horizontal side beams 46 and allow 'the propervertical spacing between beams 46.

frame 48 may be provided by any suitable means, such as a side mountedhydraulic cylinder 50. The hydraulic cylinder is fixed toone of thehorizontal side beams 46 but operates to turn a rotatable shaft 51.which in turn is connected mechanically to the frame 48. It will beappreciated that frame 48 will pivot about shaft 49 just enough to clearthe highest vertical position on the center back entrance conveyorsurface 29. The proper support and horizontal and vertical positioningfor those powered rollers 30 which are within the horizontal beammembers 46 is provided by a pair of laterally extending horizontalsupport members 52.

Since the output end 7 of the top conveyor surface is also pivotallymounted (the pivotal portion 10), it is necessary to provide the endlessflat belts 53 of the pivotal portion 10 with a suitable rigid supportframe 54. In a manner very similar to frame 48 a hydraulic cylinder 55is fixedly mounted to an outer horizontal beam 46 where it is operableto turn a rotatable shaft which is in turn mechanically connected to thepivotal frame 54.

The frame 54 pivots in a manner to sequentially com municate with thetopand middle conveyor surfaces. The frame '54 pivots about shaft 57which extends between the horizontal beams 46. Since the pivotal portionis actually the output end of both the top conveyor surface 2 and middleconveyor surface 3, it will be appreciated that there will be a smoothtransitional surface between the end of the pivotal portion 10 and theinput edge 18 of the top sheet positioner 17, so that as the individualveneer sheets move from one surface to the other, they will not becaught by an protuberances.

As previously mentioned, the bottom conveyor surface 4 is also pivotallymounted in order to pick core veneer sheets oif the endless flat belts41 which comprise the entrance conveyor surface 40. Since the poweredrollers 13 of the bottom conveyor surface are pivotal it will beappreciated that a support frame 58 will be necessary to providethesupport means for the powered rollers. The pivotal support frame 58 ismotivated by any suitable means such as a hydraulic cylinder 59 whichoperates a rotatable shaft 60 which is in turn connected throughsuitable mechanical linkage 61 to the frame 58. When the propersequential moment is reached, the hydraulic cylinder 59 will cause theframe 58 to pivot upwardly about a stationary pair of bearings at 62 andin such a manner the core veneer sheet which has been conveyed into theconveyor system 1 from the core conveyor surface loader system 39 willbe picked off the endless flat belts 41. A chain drive 63 is shown inFIG. 2 as being trained about each powered roller 13 in order to provideunitary action to rollers 13 when the bottom conveyor surface 4 isoperating.

The sheet positioner area 16 will now be described in greater detail. Aspreviously mentioned, the top sheet positioner 17 may be comprised of apiece of sheet metal having an upwardly curved surface to the outputedge 19. Since the top sheet positioner 17 is utilized to position back,center and face veneer sheets over the layup station 8 all of which havetheir respective grain directions running perpendicular to the directionof sheet travel on the conveyor system 1, it will be appreciated that ifone of these particular veneer sheets was allowed to flex, the naturalbending direction would be about a line parallel to the grain directionand perpendicular to travel. In order to properly position the center,back and face veneer sheets, it is necessary to provide the top sheetpositioner -17 with the proper angle; that is, an angle extending from ahorizontal plane through the input edge 18 upward to a line directedfrom the input edge 18 through the output edge 19 of the top sheetpositioner. In order to produce the proper amount of flexure in theseveneer sheets as they are thrown outwardly from the output edge 19 ithas been found that the ideal angle, indicated as a in FIG. 2, is on theorder of 2035. Of course the proper momentum must be provided for eachsheet as it travels over the sheet positioner 17 and it is provided by aselected speed of the independently controlled pivotal portion 10. Ithas been found through experiment that the proper conveyor surface speedis on the order of 610 feet/min. It will be appreciated that theparameters just mentioned should be taken by way of example only andthat other suitable parameters may be utilized depending upon veneersheet size or the like.

The bottomsheet positioner 20 as shown in FIG. 2 is comprised partiallyof a laterally extending sheet thrower 64. As previously mentioned, thesheet thrower 64 is the subject of a separate patent. Sheet thrower 64could be replaced by a sheet positioner similar to the curvilinearsurface of top sheet positioner 17 and thus a full detailed descriptionof thrower 64 will not be made here. However, a brief generaldescription of the details of the bottom sheet positioner 20 will begiven in order to establish an operational conveyor system 1 as depictedin the figures. Briefly, the sheet thrower 64 has a holding area 65which also extends laterally across the full length of the thrower andis adapted to receive sheets of core veneer when the thrower 64 is inits retracted position as indicated by the phantom lines of FIG. 2. Ahydraulic cylinder 66 is firmly attached to a laterally extending beamof frame 45 and extends toward the bottom portion of the sheet thrower64. The opposite end of the hydraulic cylinder is attached tothe sheetthrower 64 and thrower 64 is necessarily adapted to pivot about a point67 through an angle of approximately 40 when hydraulic cylinder 66actuates the thrower 64 from its retracted position to its fullyextended position which is the position indicated by solid lines in FIG.2. The hydraulic cylinder 66 motivates the sheet thrower 64 withsufiicient momentum so that a core veneer sheet which has been loadedinto the holding area 65 is thrown outwardly from the end of theconveyor system 1 to a suspended airborne position over the layupstation 8. A pivotal tipple 68 is provided which operates in conjunctionwith the stationary backstop 22. The purpose of the pivotal tipple 68 isto allow the core veneer sheet to fall into the holding area 65 of thesheet thrower 64 and then to clear the top of backstop 22. As a coreveneer sheet is conveyed toward sheet positioner 20 by the bottomconveyor surface 4 the tipple 68 will be in a horizontal position andthe thrower will be in its extended position. The core veneer sheet isgiven enough momentum such that it flies horizontally forward from thebottom conveyor surface 4 over the curved surface 64a of the thrower 64and hits the stationary backstop 22. The thrower 64 then retracts andthe sheet falls into the holding area 65. Just prior to the actuation ofthe hydraulic cylinder 66 to position the core sheet over the veneerstack 21 the pivotal tipple 68 is automatically moved upward through anangle of approximately 40 such that the core veneer sheet will justclear the vertical top of the backstop 22. A laterally extending openarea 69 allows each core veneer sheet which has its grain runningparallel to its direction of travel to be thrown clear of the end of theconveyor system 1 and out over the layup station 8.

As each sheet of veneer comes from the conveyor system 1, the two men onopposite sides of the veneer stack 21 will lightly clutch the sheet andallow it to fall onto the top of the stack 21. The backstop 22 serves asa guide means in order to form at least one straight side to the veneerstack. After a sufficient number of individual veneer sheets are stackedwhich form the pre-pressed plywood panels, the stack is removed from thefiat bed 23 and taken to the plant press area.

OPERATION OF THE INVENTION Although the operation of each element of theinstant invention was explained when describing the particular element ashort description of the operation of the conveyor system will be madein relation to the formation of three and five ply plywood panels.

As previously mentioned a three-ply panel is comprised of a back veneersheet with the grain running in the direction of its longer dimension, acore veneer sheet with the grain running parallel to the shorterdimension and a face veneer sheet again with the grain running parallelto the longer dimension. In a three-ply panel the back and core veneersheets each receive a coating of glue on their upper sides prior totheir entry into the central con veyor system. At the layup stationwhere each sheet is sequentially stacked to form the panels it will beappreciated that a back, core, and face sheet is the sequence and thatthis sequence is repeated until a predetermined number of panels areformed at the layup station. In the formation of three-ply panels centersheets are not utilized.

First to be conveyed toward the layup station is an individual backveneer sheet. A single back sheet is taken from its stack and positionedover the input end of the top conveyor surface by the action of thecenter-back con- 1 1 veyor surface loader system. Through this operationthe back veneer sheet will be coated with a surface of glue on its topsurface. At about this same time an individual core veneer sheet istaken from the top of its stack and through the action of the coreconveyor surface loader system is positioned over the input end of thebottom conveyor surface. In a similar manner to the back veneer sheetsthe core veneer sheet receives a coating of glue on its top surface asit passes through the softroll glue spreader. At this point anindividual face sheet is taken from the top of its stack and through theaction of the face conveyor surface loader is positioned on the inputend of the middle conveyor surface.

With all of the conveyor surfaces loaded with their respective veneersheets the sequential operation of the overall conveyor system is readyto begin. First, the top conveyor surface frame pivots upwardly to pickthe back sheet off of the center-back entrance conveyor surface. At thesame time the pivotal portion of the middle conveyor surface is in itsupper position to receive the back Iveneer sheet from the top conveyorsurface. The endless flat belts are then powered and the individual backveneer sheet travels to the output end of the top conveyor surface whereit is given sufficient momentum to be conveyed over the top sheetpositioner and out over the flat bed at the layup station. As the backveneer sheet is in the air, the two men clutch it lightly and as itgravitates downwardly they position it against the fixed back stop.

In the next sequence the bottom conveyor surface pivots upwardly pickingoff an individual core sheet from the core entrance conveyor surface.The bottom conveyor surface is then powered and a core sheet travelshorizontally toward the layup station where it runs into the fixed backstop and falls into the holding area of the bottom sheet thrower. Thehydraulic cylinder then is actuated which causes the sheet thrower tothrow the core sheet outwardly over the fixed back stop and over thelayup station where it is similarly clutched and allowed to gravitatedownwardly where it is positioned against the fixed back stop on top ofthe previously positioned back veneer sheet.

Finally, the face veneer sheet is ready to be conveyed. In the meantimethe pivotal portion of the middle conveyor surface has returned to itshorizontal position and the middle conveyor surface is now a directhorizontal surface to the top sheet positioner. The flat belts of themiddle conveyor surface are then powered and the face veneer sheettravels horizontally and is given enough momentum to propel it over thetop sheet positioner such that it is thrown outwardly and over the layupstation where it is similarly clutched and allowed to gravitatedownwardly to be positioned over the core veneer sheet. This sequence isthen repeated with the next back veneer sheet having a glued top surfacebeing positioned over the face veneer sheet of the already formedthreeply panel.

Briefly, if it is desired to form a four-ply panel which is comprised ofa back, two adjacent core sheets and a face, it is a simple matter tosequentially position an additional core veneer sheet in the formedpanel. Thus, prior to a face sheet being conveyed the bottom conveyorsurface and bottom sheet positioner will discharge two core veneersheets over the layup station in order to form the center portion of afour-ply panel. Then in a similar manner to three-ply formation the facesheet is positioned atop the two core veneer sheets.

In the formation of five-ply panels, it is necessary to utilize a centerveneer sheet. As previously mentioned a five-ply panel consists of aback veneer sheet, core veneer sheet, center veneer sheet, another coreveneer sheet, and a face veneer sheet, each sequentially stacked at thelayup station. The operation of the conveyor system in forming five-plypanels is very similar to the formation of threeply panels, howeverafter the first back sheet and core sheet are conveyed to the layupstation a center'veneer of glue onits top surface as it passes throughthe glue spreader. In a like manner the center veneer sheet is thenconveyed down top conveyorisurface and over the top sheet positioner andhorizontally outward where it gravitates downwardly to be positionedatop the first core sheet. In the meantime the core conveyor surfaceloader system has charged the bottom conveyor surface with a second coresheet and it is then conveyed and positioned for placement atop theglued center sheet. Finally the fifth-ply or in this instance the faceveneer sheet is ready to be conveyed and positioned atop the second coresheet, thereby forming the five-ply panel. The pivotal portion of themiddle conveyor surface is, of course, in its horizontal mode forconveyance of the face sheet. It will thus be appreciated that in thefive-ply formation cycle the center-back and core conveyor surfaceloader systems each are responsible for charging the top and bottomconveyor surfaces with two individual veneer sheets. In the case of thetop conveyor surface they are the back and center sheets and in the caseof the bottom conveyor surface two core sheets are positioned thereonduring a single cycle.

It will be understood by those skilled in the art, that plywood panelscontaining additional plies may be readily formed by the centralconveyor system by simply controlling the sequential operations of theseveral loader systems and the conveyor surfaces. For example, seven andnine-ply panels can be readily formed by the addition of a second centersheet and third core sheet in the case of seven-ply panels and .a fourthcore sheet and third center sheet in the case of a nine-ply panel.

In brief summary, it will be appreciated that a vertically extendinghorizontally in-line central conveyor system has been described withappropriate loader systems such that individual veneer sheets areconveyed to a layup station where plywood panels are formed. The floorspace required for the planof this machine is less than those of theprior art. Rejects are minimized by the utilization of two men who serveto scan each veneer sheet as they come from the sheet positioners. I

While a specific exampleof the preferred apparatus ha been described, itwill be apparent that many changes and modifications may be made withoutdeparting from the spirit of the invention. It should be understood thatthe appended claims include within their scope all such changes andmodifications. I

What is claimed is: l

1. A thin sheet layup machine for making sequentially arranged bondedpanels, each having at least three plies of thin sheets, comprising:

a plurality of generally horizontal; conveyor surfaces disposedvertically above one another and in line therewith, each havingan'output end thereto and means to sequentially activate and controlsaid surfaces,

a layup station positioned adjacent the output ends of said conveyorsurfaces arranged and adapted to accept thin sheets as they aretransferred individually from the output ends of said conveyor surfaces,

thin sheet positioning meansin operative communication with the outputends of said'conveyor surfaces each arranged and adapted to transfer thethin sheets individually from said conveyor surfaces to a positlon oversaid'layup station,

first conveyor loading means arranged and adapted to sequentiallyposition a thin sheet on'one of said conveyor surfaces,

second conveyor loading means arranged and adapted to sequentiallyposition a thin sheet onto another of said conveyor surfaces,

third conveyor loading means arranged and adapted to position a thinsheet on one other of the plurality of conveyor surfaces, and" means toapply an adhesive surface over at least one 3,725,183 13 14 of the facesof at least two preselected thin sheets References Cited as they areconveyed from their respective conveyor UNITED STATES 1P ATENTS loadingmeans over their respective conveyor surfaces to said thin sheetpositioning means. 3616090 110/1971 i 156*566 X 2. A thin sheet layupmachine as in claim 1 wherein 5 4 9/1971 et X said layup station iscomprised of a generally horizontal, 1418x065 12/1969 OBnen 156' 563vertically adjustable flat bed and at least one vertically 34375454/1969 Bacon 156*559 X extending airstop member arranged so that eachthin 3367823 2/1968 Clausen et a1 198-35 X sheet as it falls toward saidflat bed can be aligned against 3312327 4/1967 ClaPP et a1sazidhfirslgcptsnznlgleghthereby allowing a unlform stack 1 PHILIP DIERPrimary Examiner 3. -A thin sheet layup machine as in claim 1 wherein US G X R said adhesive applying means are positioned between theirrespective conveyor loaders and conveyor surfaces. 156-565, 198-45

